What is dual pricing?
You post two prices, a cash price and a card price, and the customer picks. It works the same for credit and debit cards.
Both prices are shown before the customer pays, on the menu, shelf tag or invoice. The card price covers the cost of taking the card, so you keep the full amount either way.
For example
A café menu shows a latte at $5.00 cash and $5.17 card. Whether the customer taps a credit card or a debit card, they pay the card price.